High-speed VCSEL laser epitaxial structure and preparation method therefor

Abstract

The invention provides a high-speed VCSEL laser epitaxial structure. The laser epitaxial structure comprises a GaAs substrate; a GaAs buffer layer, an N type doped DBR, an active layer, an oxidization limiting layer, a P type doped DBR and an ohmic contact layer are deposited on the GaAs substrate by adopting MOCVD in sequence; and the oxidization limiting layer is formed by multiple Al<1-x>Ga<x>As epitaxial layers with freely adjustable Ga components, wherein X is the Ga element component. According to the laser epitaxial structure, the multiple layers of Al<1-x>Ga<x>As with certain thickness and jumping components are adopted to form the oxidization limiting layer; and the front-end shape of the oxidization limiting layer can be changed by adjusting the components in each layer of Al<1-x>Ga<x>As, so that a lens structure can be formed at the front end of the oxidization limiting layer, and photon scattering loss can be lowered, thereby improving the modulation bandwidth of the VCSEL. The laser epitaxial structure has the following advantages: 1) by adjusting the ratio of Ga in the oxidization limiting layer, the oxidization rate of the oxidization limiting layer is lowered, the oxidization can be controlled easily, and the product yield of the VCSEL chip is improved; and 2) the oxidization limiting layer is high in thickness and low in intrinsic stray capacitance.

Description

technical field [0001] The invention relates to the technical field of semiconductor optoelectronics, in particular to a high-speed VCSEL laser epitaxial structure and a preparation method thereof. Background technique [0002] Vertical cavity surface emitting laser (VCSEL) is a semiconductor laser that emits light in the direction perpendicular to the substrate on which the laser is formed. Compared with edge emitting semiconductor lasers (FP, DFB, etc.), it has small temperature drift, low threshold, and fiber coupling. High efficiency, easy integration, packaging, high speed (up and down at 100ps level) and other characteristics, it is the preferred light source in ultra-high-speed short-distance optical interconnection equipment, widely used in large-scale data centers, connections in supercomputers, and in the continuous demand for data analysis Driven by the rise, it is expected that the future output value of VCSEL will exceed one billion US dollars. Such as figure ...

AI Technical Summary

Problems solved by technology

[0005] 1) The oxidation rate is fast, and the light exit aperture of VCSEL is difficult to control, resulting in low yield of VCSEL;

[0006] Cause: The oxidation limiting layer of traditional technology generally uses AlAs as the oxidation limiting layer. The thinner the AlAs layer is, the faster the oxidation rate is, while the oxidation pore size of VCSEL is generally 6-8um, and it is extremely difficult to stably and repeatedly control the oxidation pore size, resulting in VCSEL preparation low yield;

[0007] 2) Large parasitic capacitance affects the modulation rate of VCSEL;

[0009] 3) The stress of the oxide layer is large, and the epitaxial layer is easy to peel off after oxidation;

[0010] Cause: The AlAs oxidation limiting layer is used. Since the lattice constant of AlAs is smaller than the lattice constant of GaAs, AlAs will generate large tensile stress during growth, and the epitaxial layer will be easily peeled off after oxidation, which will affect the reliability of the device.

[0011] The above-mentioned traditional technology uses a thin oxidation-limited layer (less than 15nm), and a lens structure can be formed at the front of the oxide layer to reduce the scattering loss of photons, but it will cause the above-mentioned disadvantages

Once the thickness of the oxide layer is thickened, the front end of the oxide layer will be arc-shaped (such as figure 2 shown), the scattering loss of photons will increase, which will affect the modulation bandwidth of VCSEL

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